This invention relates to a novel carbazole derivative luminescent compound. More particularly, this invention relates to a novel carbazole derivative luminescent compound, which is used for an EL (electroluminescence) light emission element and can emit lights of various colors when an energy such as electric energy or electromagnetic energy is applied thereto.
The EL elements can easily emit visible lights of various colors such as blue, yellowish green or red depending upon kinds of compounds. A great number of light-emitting compounds have been researched and developed.
These compounds may include, for example, aluminum-8-hydroxyquinolinolate complex derivatives, oxadiazole derivatives, triazole derivatives, distyrylallylene derivatives, coumarin derivatives, bis(styryl)amine derivatives.
These compounds hitherto used have problems such as high cost of production for such reasons that their starting materials are peculiar, they are produced through many process steps, the process conditions are peculiar, and the yield is low. Thus, only a few of these compounds have put to practical use. The compounds put to practical use have been desired to be low in their production cost.
Among the compounds emitting a blue, yellowish green and red light, the compound emitting a clear red light has been particularly desired. That is, the maximum luminescent wavelength of red light emitted by conventional CRT displays is 625 nm. In order to obtain a clearer red light, a sharp peak of wavelength must be produced within the range of 630 to 640 nm, and has been desired.
The object of this invention is to solve the problems above. That is, the object of this invention is to provide a novel illuminant, which can be produced with ease and at low cost.
Another object of this invention is to provide a novel red illuminant having a maximum luminescent wavelength of 600 to 700 nm.
A still further object of this invention is to provide a novel carbazole derivative luminescent compound emitting a light having the desired luminescent wavelength varying depending upon the kind of substituents of the derivatives.
To achieve the objects above, this invention is a carbazole derivative luminescent compound having Formula 1:
wherein A is an electron-donating group, and B is an electron-attracting group.
In a preferred embodiment of the carbazole derivative luminescent compound of this invention, the electron-donating group is an alkyl, haloalkyl, aminoaryl, alkylaminoaryl, or alkoxyaryl group. The alkyl group, the haloalkyl group, and the alkoxy group of the alkoxyaryl group have a carbon number of 1 to 20, respectively. The alkylaminoaryl group includes a monoalkylaminoaryl group and dialkylaminoaryl group. The alkyl group of this alkylaminoaryl group has a carbon number of 1 to 20. The above-mentioned electron-attracting group is an electron-attracting ethenyl group or aldehyde group.
In another preferred embodiment of the carbazole derivative luminescent compound of this invention, the above-mentioned electron-attracting group is the ethenyl group having Formula 2:
wherein Z is hydrogen atom, cyano group or an ester group, and at least one of the three of Z is the cyano group or ester group, or the aldehyde group.
In a further preferred embodiment of the carbazole derivative luminescent compound of this invention, the electron-attracting group is the electron-attracting ethenyl group having Formula 3:
wherein Z is hydrogen atom or cyano group, and at least one of the two of Z is the cyano group, and D is an aryl group having at least one electron-attracting group, or the aldehyde group.
In a still further preferred embodiment of the carbazole derivative luminescent compound of this invention, the above-mentioned D is an aryl group having at least one of fluorine-containing electron-attracting groups.